Battery charging system



Nov. 25, 1947. L. P. CRONYALL 2,431,311

BATTERY crumeme SYSTEM Filed Dec. 6, 1944 2 Sheets-Sheet 1 NOV. 25, 1947. p. QRQNVALL 2,431,311

I BATTERY CHARGING SYSTEM Filed Dec. e, 1944- 2 Sheets-Sheet 2 Patented Nov .-.25, 1947 nar'rnar cnaaomc. srs'rm Lara Per Cronvall, Stockholm, Sweden, assignor to International Standard Electric Corporation,

New York, N. Y.

Application December 6, 1944, Serial No. 566,887

In Sweden December 8,1943

Claims. 1

This invention relates to charging of batteries having a voltage sensitive load which may be intermittently connected thereto, particularly of the typ in which the charging takes place irom an A. C. supply over a rectifier. One object of the invention is to provide an improved battery charging control permitting high speed charging at increased voltage without subjecting the load to detrimental voltages.

Another object is to .provide a control system of this kind automatically preventing supercharging 'of the battery.

With the above and other objects in View the invention consists in the combination and arrangement of parts hereinafter fully described and illustrated in the accompanying drawings and pointed out in the claims hereunto appended.

The. invention is diagrammatically illustrated by way of example in the acompanying drawings in which Fig. 1 is a circuit arrangement embodying one form of my invention.

Fig. 2 is a modification of Fig. 1. 1

Fig. 3 is a circuit diagram illustrating a second embodiment of my invention with additional control facilities.

Fig, 4 is a circuit scheme of a third embodiment of my invention.

In all of the figures on the drawing I represents an A. C. supply and 2 a transformer for delivering alternating current from supply I to a dry rectifier 3 charging an accumulator battery 4 having a load 5 adapted to be connected and disconnected therefrom.

For controlling the charging in the embodiment shown in Fig. 1 there is used a saturable core reactor arrangement having an inductance 6 passing the alternating current and two direct cm'rent exciting windings l and 8 connected in series aiding when the load is off and traversed by the direct current output of rectifier 3. The

age will, however, be dependent on the value of the charging current flowing through windings I and 8 so that when said'current during the course of charging falls below a predetermined limit the charging voltage is automatically reduced to a value preventing supercharging of battery 4.

Fig. 2 shows a similar arrangement differing from that illustrated in Fig. 1 only in the respect that two resistances ll and II connected in series are in combination connected in parallel to winding 8. Resistance ll can be shortcircuited at contact 9. The mode of operation is substantially equal to that set forth with reference to Fig. 1.

The embodiment illustrated in Fig. 3 an auxiliary saturable core reactor arrangement including an inductance l2 traversed by alternating current derived from the input of rectifier 3 over transformer -l3 and supplying winding 8 of the main reactor 6, l, 8 over rectiher It. At i5 there is shown a D. C. excitation winding for the auxiliary reactor supplied with D. C. winding I can be short-'circuited bya contact 9 which by means of a relay III is so dependent on the external load 8 that it is open when the external load is off and'closed when said load is on. In the former'case the A. C. and.

current irom a rectifier i6 receiving A. C. from the input 01 rectifier 3 over transformer ll. In addition the auxiliary reactor comprises a D. C. excitation winding 18 connected across the output op re ctifler 3 and a D. C. excitation windin 19 for compensating voltage variations of supply i and fed with D. C. from a rectifier 20 connected across the input oi transformer It.

In this embodiment contact 9 is supposed to be open when the load is on and by means 0! resistance 2| the output voltage of rectifier 8 with the load 5 on can be adjusted to any desired value which by suitable proportioning of the auxiliary reactor I! can be maintained with the desired accuracy, such as 21%. such accuracy being irequently required, for instance, in the operation of telephone systems.

When the load 5 is dis-connected contact 8 closes and the auxiliary reactor 12 is thereby through winding it operated by an additional exciting voltage from rectifier I8 proportional to the charging current. Winding 8 is thereby charging operation'then continues substantialoofiharging voltage and. charging current. The

ly .in the manner described 1 with reference to Fig. 1.

In the arrangement illustrated in Fig. 4 exciting winding 8 isconnecte'd in parallel to the batcomprises 1 tery 4 when contact 9 is closed and as regards its exciting eflect acts in opposition to winding 1. In addition a voltage relay 2 2 and two resistances R1 and R: are provided. With the external load 5 on and contact 9 closed constant charging voltage regulation will be secured by means of reactor 6, I, 8. When the load 5 is disconnected and contact 9 thus opened the direct current through winding 8 will also pass through resistance R1 and winding of relay 22 resulting in a decrease of the current through winding 8, whereupon the resulting excitation of reactor 8, I, 8 will increase whereby the charging voltage rises. When the latter has reached a predetermined value relay 22 pulls up and connects resistance R: in circuit, whereby the charging voltage is reduced to the desired value preventing 4 on the charging current that the charging voltage is automatically reduced when the charging current falls below a predetermined value.

3. An arrangement according to claim 1 wherein said means to control comprises a D. C.- excitation circuit tor said choke coil and a contact for controlling said excitation circuit, said contact being operated in response to the connection and disconnection of said load.-

4. An arrangement according to claim 1 wherein said means to control comprises a D. C. excitation circuit for said choke coil, an auxiliary choke coil controlling said excitation circuit and provided with a D. C. excitation circuit and a contact for controlling said lastmentioned excitation circuit, said contact being operated in response to the connection and disconnection of said load.

5. An arrangement according to claim 1 wherein said means to control comprises a D. C. excitation circuit for said choke coll, a two position contact under the control 01' said load and a relay, said relay in one position of said contactbeing under the influence of the battery voltage for regulating said excitation circuit.

LARS PER CRONVAIL REFERENCES CITED The following references are of record in the means to control the voltage of said choke coil, m of this patent:

said means being connected to the output circuit of said rectifier to increase the charging voltage in response to the disconnection of said load.

2. An arrangement according to claim 1 wherein said control with said load off is so dependent 1,916,307

UNITED STATES PATENTS Name Date Beetem Feb. 3, 1931 Gilson July 4, 1933 Number 

